It is known in cutting tool holders to effect adjustment of the cutting tool by rotation of an internally screw-threaded wheel having graduations thereon. The wheel is rotatably mounted in a body of the holder and engages an externally screw-threaded shaft upon which the cutter is mounted in use. The shaft is mounted in the body against rotation relative thereto but is axially moveable relative to the body upon rotation of the wheel. The graduations on the wheel provide a visual indication of position of the cutting tool relative to the cutting tool holder body. With such a manual adjustment mechanism, the cutting tool can be set manually to an accuracy of about 10 .mu.m.
It is an object of the present invention to provide an improved cutting tool holder assembly which is compact and which enables the cutting tool to be set to a high degree of accuracy.